Power transmission



Jan 8, 1 946. B. READMAN ET'AL 2,392,564

POWER 7 TRANSMISSION Filed Sept. 9, 1940 INVENTORS BERNARD L. READMAN 8. ROBERT A. SHARTLE ATTORNEY Patented Jan. 8 1946 rowan TRANSMISSION Bernard L. Readman, Detroit, Micln, and Robert A. Shartle, Rockford, Ill., assignors to Vickers Incorporated, Detroit, Mich., a corporation of Michigan Application September 9, 1940, Serial No. 355,918

(01. (vii-'52) 3 Claims.

This invention relates to power transmissions, particularly to those of the type comprising two or more fluid pressure energy translating devices one of which may function as a pump and another as a fluid motor. v

The invention is more particularly .concerned with a hydraulic power transmission system adapted for operating a marine steering gear. Electrohydraulic steering gears have long been in practically universal use for operating the rudder on vessels of the larger and faster classes. As used in this class of service, such steering gears are rather costly and prohibit the use of similar equipment in a large field of marine applications where economy in construction is an important consideration. A large number of freighters,

sure to operate the ram a pair of alternately ,usable pumps 28 and 28 are provided and may be tankers, trawlers, ferries, 'etc., are compelled to get along without the many advantages of hydraulic steering because of the excessive cost of such steering gears asare commonly used in marine service.

It is accordingly an object of the present invention to produce. an electrohydraulic steering gear, of very low first cost yet which provides satisfactory operation in the class of marine service above indicated.

A further object is to provide an electrohyn draulic steering gear of this character wherein duplicate standby equipment may be provided at low costso as to enable a vessel to proceed in the event of dearrangement of the normally used portions of the steering gear.

It is also an object to provide an electrohydrauic steering gear of this character which is economical in operation and maintenance as'well as in first cost and which is reliable and durable for a long and useful life.

Further objects and advantages of the present invention will be apparent from the'following description, reference being had to the accompany ing drawing wherein a preferred form' of the present invention is, clearly shown.

- In the drawing the single figure is a diagrammatic view of a hydraulic power transmission system embodying a preferred form of the pres- I ent invention.

'aft rudders designated in and I2, respectively.

The rudders are connected by a cable system 4 and IS with hydraulic rams l8 and 28 slidable in stationary cylinders 22 and 24 which thus constitute the usual hydraulic motor or ram for rudder operation.

For the purpose of supplying fluid under presdriven by separate prime movers suchas electric motors 38 and 32. The pumps are arranged to withdraw fluid from a supply tank 34, their discharge conduits 36 and 38 extending through checkvalves 48 and 42 to a common pressure supply line 44. The latter has the customary overload pressure relief valve 45 for bypassing the pump delivery to tank through a return conduit .46 whenever a predetermined pressure is exceeded in the supply line 44.

It is evident that either of the pumps 26 or 28 may be operated at one time and that the check valve associated with the other pump will prevent the application of pressure in the supply line 44 from reaching the idle pump. The purpose The latter has cylinder ports 50 and 52 which are connected by conduits 54 and 56 with the opposite ends of motor 22'. The valve 48 is also provided with return ports 58 and 68 which are connected together by a conduit 62 leading to the pressure port 64 of a duplicate valve 86 which may be identical to the valve 48 The valve 48 has a three-land spool 68 provided with a central internal passage 18 which communicates through radial bores with the three ports 41, 58 and 60 when the spool 68 is in its neutral position. Pusher-type solenoids l2 and 14 .are provided at opposite ends of the valve to shift the spool 68 to the left and right, respectivelye A spring-centering mechanism 16 normally retains the valve spool- 68 in the neutral position illustrated when neither solenoid is energized.

The valve 86 has its cylinder ports 18 and 88 connected by conduits 82.,and 84 with the conduits 54 and 56 so that, with respect to the cylinder ports of the valves 48 and 66, the two valves are connected 'in "parallel with the cylinder 22. The tank ports. 88 and 88 of valve 66 are joined by a conduit 82 with thepressure port 94 of a third reverse valve 96 which is also identical in v I construction with thevalve 48. It will thus be seen that the two valves 48 and 8B are connected in series as regards the pressure supply and return conduits.

' The cylinder ports 88 and I08 of the valve v lever I12.

site ends of cylinder 24. The tank ports I86 and I88 of valve 96 are connected together and communicate with the tank 34 by the conduit H8.

Thespools H2 and H4 of the valves 66 and 96,

conduits 64 and 82, ports I8 and 88 of valve 66, conduit 92, valve 86 and conduit IIII to tank. Thus the rudder is shifted counterclockwise which in turn actuates the cable connection I68 and respectively, are adapted to be shifted .to the left y i by solenoids H6 and 'II8 and-to the right by solenoids I28 and I22. Spring-centering mech'- anisms I24 and I26normally bias the spools to their central neutral positions as illustrated.

For the purpose of selectively energizing the various solenoids, an electrical control circuit is provided as follows: A pair of snap-acting limit switches I28 and I38 which are spring biased to normally open position are arranged to control circuits I32 and I34 extending, respectively, to a double-pole, double-throw, selector switch I36.

The selector switch. is adapted to selectively connect the circuit conductors I32 and I34 either with conductors-I38 and I48 leading to the solenoid I16 and I28, respectively, or to the conductors I42 and H4 leadingto the solenoids I2 and I4, respectively. Connection to a suitable source of electricpower ismade atone side of the limit switches'indicatedat I. and at one side of the solenoids indicated at'lfi. Similarly limit switches I46 and I48control circuits I68 and I62 extending directly to the solenoids H6 and I22, respectively; j l

The limit switches I28 and I38 are normally spring biased to open position and may be closed by shifting of a lever I64, the fulcrum I56 of which shifts the fulcrum I66 to the left.. So long-as the lever I62 continues to be moved at a rate corresponding to the speed of movement of rudder I8,

limit switch I38 will remain closed, and the rudder will continue to move. However, as soon as the movement of lever I62, is discontinued, the rudder will continue on a small distance! carrying the fulcrum I66 and thereby swinging the lever I54 counterclockwise about the pivot point on link I68 to open limit switch I38. The partsiaccordingly come to rest with the rudder I8 and lever I62 in a new position, the valve 66 returning to its neutral position. A similar actioh resuits if the lever, I62 be moved to the rightcausingjopposite movement of rudder I8. It will be uli'ilerstood that, due to the diagrammatic showing, the movements required at lever I64 to control switche I28 is carried by a cable system I68 connected with the rudder I8. An intermediate point of the lever I64 is connected by a link I68 with a hand lever I62. Similarly the switches I46 and I48 are under the control of a floating lever I64,-the fulcrum I66 of which is carried by a cable system I68, a

link "8 connecting the lever I64 with a hand It will be seen that the cable systems I58 and th difierential control of the rudder position and the hand lever position to produce a follow-up action.

In'operation, assuming that the pump 26 and,

motor 38 are in operation and that the selector spools will lie in theirneutral positions, as shown 7 .in the drawing. The'pump delivery is accordingly directed through conduit 44, port-41, passage I8, ports-68 and 68, conduit 62, port/64, valve 66, conduit 92, valve 96, and conduit I ,I8 to tank. This 4 path imposes negligible resistance to the passage of fluid so. that the motor 38'operates at substantially no load. It will also be noted that the oil in the opposite ends of cylinder 22 i trapped at the cylinder ports of both valves 48 and 66 so that the rudder I8 is effectively locked in position. The

1' I68 acting on the shiftable fulcrums I56 and I66 constitutes a follow-back system from the rudders I8 and I2 whereby the limit switches are under and I38 are much greater than would be the case in actual practice.

The operation of rudder I2 from lever II2,is, similar to that described in connection with rudder I8. Y

Should the valve 66 or its-operating solenoids or circuit become disabled, the rudder I8 can be operated under the control of valve 48 by shifting the selector switch I36 to-connec't solenoids 1,2 and 14 with the limit switches I28. and I38.

The action-under these conditions is identical to that previouslyv described. It will be noted that no connections in the hydraulic circuit have to I be changed for making this shiftover. The same 7 is true, of course, should one ofthe pumps or motorsbecome disabled. It will thus be seen that pletely unloaded at all times when the rudder is not being operated and in which the rudder is hydraulically locked at the same time.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it-i-is to be understood that other forms might be adopted, all coming within the scope of the claims which follow; Y

What is claimed is as follows: I

1. In a hydraulic marine steering gear thecombination with a continuouslyndriven. fixed displacement pump and a double-acting hydraulic ,ram for'operating a. rudder, of a hydraulic circuit connecting the pump with the ram, said circuit including a multi-way reversing valve having a neutral position in which the p mp is bypassed and theram is hydraulically-locked, and a standby reversing valve of similarconstruction, said and to the pump and in parallel with respect to T the. lines to the ram.

same is true of rudder I2 due to the blocking of cylinder ports 98 and I88 of valve 96.

If it is desired to shift the rudder I8 to a new position, the handle I62 may be shifted, for ex--' ample, to the left, thus closing limit switch I38 1 and energizing solenoid I28.v Spool II2 accordingly shifts to the right connecting the pressure supply from port 64 to port 88 thus directing fluid to the upper end oi. cylinder 22. Fluid discharged from the lower end of cylinder 22 passes through 2. In a hydraulic power transmission system the combination with a pump forming a source of fluid under pressure and a hydraulic motor to be operated by the pump, of a hydraulic circuit connecting the pump with the motor, said circuit including a multi-way reversing valve having a neutral position in which the pump is bypassed, and

- a standby reversing valve of similar construction, said valves being connected in series with respect -,3. In a hydraulic marine steering gear the combination with a continuouslydriven fixed displacement pump and a double-acting hydraulic ram for operating a rudder, of a hydraulic circuit connecting the pump with the ram, said circult including a multi-way reversing valve having a neutral position in which th pump is bypassed and the ram is hydraulically locked, electricallyactuated means for selectively shifting said valve substantially instantaneously to a fully open position at either side of neutral position, whereby the snap-acting circuit controlling means for controlling said shifting means, and a follow-up device for operating said circuit controlling means in response to the differential positions of the rudder and a manually controlled member.

BERNARD L. READMAN. ROBERT A, SHARTLE. 

